Double tube core barrel which is lowered through drill pipe

ABSTRACT

The double tube core barrel of the invention, which is to be lowered through a drill pipe, has a locking system between inner and outer tubular parts thereof which is particularly characterized by its sturdy and simple construction. Such locking system has two free, unlinked oscillating locking plates, the closing of the plates for releasing the locking system being accomplished by means of a sliding sleeve of special construction. This system eliminates every kind of failure of the locking system due to accidental deflection of the locking parts of classical systems provided with links. The core barrel of the invention also preferably has a novel system for breaking the core. Such core breaking system is provided with two core retainers. The supplementary core retainer is mounted on the outside tube; this allows the avoidance of traction overloading of the inner tube by reason of the taking over of these stresses by the outside tube. The system of the invention can be applied to core barrels with large sizes. When coring in soft rocks, the supplementary core retainer can be omitted.

United States Patent Constantinescu et a1.

[ June 26, 1973 Primary Examiner-David H. Brown Attorney-Arthur O. Klein [5 7] ABSTRACT The double tube core barrel of the invention, which is to be lowered through a drill pipe, has a locking system between inner and outer tubular parts thereof which is particularly characterized by its sturdy and simple construction. Such locking system has two free, unlinked oscillating locking plates, the closing of the plates for releasing the locking system being accomplished by means of a sliding sleeve of special construction. This system eliminates every kind of failure of the locking system due to accidental deflection of the locking parts of classical systems provided with links. The core barrel of the invention also preferably has a novel system for breaking the core. Such core breaking system is provided with two core retainers. The supplementary core retainer is mounted on the outside tube; this allows the avoidance of traction overloading of the inner tube by reason of the taking over of these stresses by the outside tube. The system of the invention can be applied to core barrels with large sizes. When coring in soft rocks, the supplementary core retainer can be omitted.

1 Claim, 4 Drawing Figures DOUBLE TUBE CORE BARREL WHICH IS LOWERED THROUGH DRILL PIPE [75] inventors: Dorin Constantinescu, Pacii; Sever Cruceanu, Grivitei; Eugen Spataru, Straduintei; Nicolae Mereanu, Frumoasa, all of Romania [73] Assignee: Institutul de Proiectari si Cercetari Pentru Utilay Petrolier-IPCUP, Bucharest, Romania [22] Filed: Mar. 19, 1971 [21] Appl. No.: 126,029

[52] U.S. Cl. 175/246, 175/255 [51] Int. Cl E21b 9/20, E21b 25/00 [58] Field of Search 175/246, 248, 249, 175/251, 255

[56] References Cited UNITED STATES PATENTS 3,461,981 8/1969 Casper et al 175/246 2,829,868 4/1958 Pickard et al..... 175/255 X 2,671,642 3/1954 Stokes 175/255 2,668,037 2/1954 Stokes.... 175/255 3,103,981 9/1963 Harper....; 175/246 X 3,305,033 2/1967 Pickard et al..... 175/246 X 3,340,939 9/1967 Lindelot 175/246 L b, 1Q

. j 3L i IZ DOUBLE TUBE CORE BARREL WHICH IS LOWERED THROUGH DRILL PIPE This invention is related to a double tube core barrel which can be introduced through drill-pipe when drilling with drilling rigs or core drills.

The invention has among its objects the provision of a novel core barrel of simple, sturdy construction which has a long productive life.

There have heretofore been available double tube core barrels which can be introduced through drill pipes. See, for example the U.S. Pat. to Hall et al., No.

3,292,717, Dec. 20, 1966. In some of such prior art,

double tube core barrels the assembly of the core holding tube in the body of such core barrel while coring being achieved bymeans of two mobile parts which can slide radially by means of a spring. One such construction is shown in the US. Pat. to Svendsen, No., 3,346,059, Oct. 10, 1967. In certain of these prior art core drills the fixing'or locking parts are provided with two bolts which can slide in a trapezoidal window cut into a lock support assembled at the upper part of the core-holding tube. When pulling the lock support upwardly with a slip socket, with both bolts in contact with the sides of the trapezoidal window, the bolts pull the locking parts in a part-fastening direction, thus permitting the assembly tube core support to be extracted. This mechanism for freeing the core-holding tube has the disadvantage that the accidental breaking of one of the two bolts makes the extracting operation of the core-holding tube assembly very complicated ,and expensive.

There have also been available double tube core barrels, which can be introduced through drill pipes, in which the breaking stress of the core, when extracting the core-holding tube assembly, is transmitted to the outer barrel of the core barrel body to protect the coreholding tube against large tensile stresses. In such core barrels the stress transmission is achieved by propping the core-holding tube against a circular shoulder machined in the core barrel head and by suddenly raising the drilling string from the bottomof the well. This system is limited to double tube core barrels of small diameter, since the core-holding tube is supported at its upper end by a spiral spring.

The core barrel according to the invention eliminates both of the above-mentioned disadvantages. For looking the core-holding tube in the outer barrel of the core barrel it uses a pair of plates actuated by a spring placed between them, the plates being freely mounted into a seat made in a lock support. The lock support is assembled by screwing it to an axially disposed rod which is fixed in a case provided with roller bearings, such case being screwed to the core-holding tube. The plates are covered by a case assembled at the upper part of an extraction head by means .of a first bolt, and at the lower part to the lock support by means of another, second bolt, the second bolt being fixed in the walls of the case; the case and second bolt move axially, the second bolt moving in a slit machined in the lock support. The case is provided with two windows,

ment of the case relative to the lock support, slides upon inclined surfaces of the plates, pushing them into their seat in the lock support. In order to protect the core-holding tube against high traction stresses, the

core barrel preferably utilizes a first core retainer, mounted into a case at the lower part of the coreholding tube, and also a second, supplementary core retainer, mounted between the core cutter head and an adapter between the core cutter head and its body. The seat of this second core retainer has a larger taper, i.e., a bigger conicity than that of the first retainer, so that when raising the drilling string from the bottom of the well, the supplementary core retainer is actuated first and forces the whole tractile force to strain the outer barrel of the core barrel exclusively. At the end of the operation of pulling the core-holding tube out of the drill-pipe, the supplementary core retainer is freed. When the core barrel is used for core drilling in soft formations, the supplementary retainer can be dismounted, since only the retainer in the core-holding tube is then required.

The accompanying drawings illustrate a preferred embodiment of the double tube core barrel according to the invention. In the drawings:

FIG. 1A and 1B, when assembled, form a view in longitudinal section through the core barrel body a small portion of the core barrel body being broken away for economy of space in illustration;

FIG. 2 is a view in cross-section through the core barrel, the section being taken along line 2-2 of FIG. 1A; and

FIG. 3 is a view in cross-section through the core barrel, the section being taken along the line 3-3 of FIG. 1A.

' In the embodiment of the core barrel shown in the drawings, the outer barrel of the core barrel consists of an upper adapter 1 which is screwed at 1a onto the lower end of a drill-pipe (not shown), an adapter 2 which has two axially spaced downwardly converging frusto-conical annular recesses a and b, an outer barrel 3 (FIG. 1B) screwed to the lower end of adapter 2, and

through which the plates can be selectively pushed by I an adapter 4 screwed to barrel 3, adapter 4 being provided on its outer surface with calibration and guiding sectors or ribs c, and inside at its lower end with a counterbore d. To the lower part of the adapter 4 there is screwed an annular cutter head 5; cutter head 5'forms an annular kerf at the bottom of the drill hole in rock, and forms a rock core (not shown) extending axially upwardly within the cutter head.

The core cutter head 5 is provided with a downwardly converging frusto-conical axial bore 5a in which a resilient, contractible core retainer 6 slides axially. Between the outer barrel 3 and the adapter 4, there is positioned a centering ring 7. v

The inside assembly of the core barrel includes a pulling head 8, which ends at the upper part with a conical formation to which the extraction device (not shown) for the core-holding tube attaches. The pulling head 8 is fixed to a tubular case 9 by a cross bolt 10 fixed in holes 3 made into case 9. Somewhat axially below the holes 3 the case 9 has also two diametrically opposed windows h, the lower edges of windows h being conical surfaces i. The case 9 is assembled to a lock support 11 disposed within adapter 2 by a cross bolt 12 similar to bolt 10. A cross slot j, in the bolt 12 is placed, machined in the lock support 11 allows an axial displacement of the case 9 relatively to the lock support 11. To allow circulation of the drilling fluid, the body of the lock support is provided with two crossing angular canals m. In a seat formed as a cross slot machined in the lock support 11, two non-articulated plates 13 are mounted for free radial movement; plates 13 are'pushed radially outwardly by a leaf spring 14 of X form placed between them. The plates 13 have, at their inclined part, lateral surfaces which converge in a downward direction. To the lock support 11 there is screwed an axial rod 15, the rod being fixed by a nut 16. The lower end of the rod 15 is fixed to a case 17 in the tubular coaxial upper part of which there are roller bearings 18. At the lower part of the case 17 for the roller bearings, in a cylindrical axial bore n there is a valve seat 19, fixed by an elastic ring 20. A washing ball 21 assures discharging above the core drilling fluid which flow through orifices into the bore n; such arrangement prevents an eventual tendency for reverse circulation along the core.

A core-holding tube 22 is screwed into the lower end of the case 17. The lower end of the tube 22 is provided.

with a case 23 having a conical bore P in which a supplemental core retainer 24 slides axially.

The lower assembly of the core barrel consisting of the core-holding tube 22, the lock support 11, the case 9, the plates 13, the case 17 for the roller bearings, and the axial rod are loweredthrough the interior of the drill-pipe string, its weight being sufficient to cause it to descend into the drill hole until the body of the lock support 11 rests upon annular shoulder'b in the inner wall of the adapter 2. During the lowering ofthe assembly down the drill-pipe, the plates 13 slide upon the inner walls of the drill pipes;' when the assembly stops its downward travel by reason of the-engagement of the lock supportll with the shoulder b, the plates 13 move radially away from each other under the influence of the spring 14, and thus enter the recess )1 inthe adapter 2. The accidental raising of the core-holding tube in the outer barrel during the coring operation is prevented by engagement of the sharp shoulders at the upper ends of plates 13 against the shoulder at the lower end of the upper adapter 1, as shown in FIG. IA.

As the coring cutter 5 and the assembly above it ad vance downwardly, the rock core which is thus being formed pushes the retainer 6 upwardly until the latter engages the shoulder d, so that the lower core retainer the outer barrel, thereby eliminating the source of fre-.

quent damage and. jamming in the above-described prior art devices. The core barrel according to the invention also assures protection of thecore-holding tube against large tensile or traction stresses when breaking the cores of hard rocks. 7

Although the invention is illustrated and described with relation of one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but is capable of numerous modifications within the scope of the appended claims.

What is claimed is:

1. In a double tube core barrel adapted to be introduced through drillpipes, said core barrel having an outer tubular casing and an inner, core-holding tube adapted to be disposed within said outer casing in a lowered position near the bottom thereof, the improved mechanism for selectively holding the coreholding tube in said lowered position comprising a lock support disposed coaxially of the core-holding tube and rotatably connected thereto by a spindle device screwed into the lock support and core-holding tube r such parts, thelock support beingin the form of a body ing plates having locking shoulders on their radially outer axially upper ends disposed in said slot'for nonpivotal radial reciprocation therein, a compression spring mounted between the locking plates for constantly urging them radially outwardly in said slot, a

can no longer move upwardly. After this, the core penetrates into the upper, supplementary core retainer 24, and pushes it upwardly until it engages the lower end of the core-holding tube 22. As the length of axial travel of the retainer 6 is smaller than the permissible stroke of the retainer 24, and the diameter of the bore is larger than that of the bore p, when the drill pipe string is raised from the bottom of the drill hole in order to break the core, the first core retainer actuated is the retainer 6, so that the core-breaking stress will be transmitted directly to the outer barrel of the core barrel.

At the next pulling operation of the core-holding tube 22, the retainer 6 is released, thereby freeing the core to be pulled out. During the initial pulling phase of the core-holding tube 22, the case 9 is displaced upwardly until the bolt 22 reaches the upper limit of the slotj of the lock support 1 1. At the same time, the conical surface i of the recesses h of the case 9 slides upon the conical surface k of the plates 13, which are thereby retracted radially inwardly from the recess h and are locking plate retracting and covering tube mounted within the outer casing for axial reciprocation with respectthereto, a core-holding tube pulling head fixedly connected to the upper end of the locking plate retracting tube, lost motion means connecting the lower part of the locking plate retracting tube to the lock support so that the locking plate retracting tube may be axially lifted to a limited degree relative to the lock support upon the initial lifting of the pulling head, the locking plate retracting tube having two diametrically disposed windows therein through which the outer ends of the locking plates can be pushed by the compression spring, a locking seat in the inner surface of the outer casing selectively lockingly receiving the shouldered outer ends of the locking plates, the lower outer surfaces of the locking plates axially below the shoulders v thereon being inclined radially outwardly in an axially locking seat in the outer casing.

t t It I! t 

1. In a double tube core barrel adapted to be introduced through drill pipes, said core barrel having an outer tubular casing and an inner, core-holding tube adapted to be disposed within said outer casing in a lowered position near the bottom thereof, the improved mechanism for selectively holding the coreholding tube in said lowered position comprising a lock support disposed coaxially of the core-holding tube and rotatably connected thereto by a spindle device screwed into the lock support and core-holding tube and carrying bearings to permit the relative rotation of such parts, the lock support being in the form of a body having a diametrically and axially extending slot therethrough, a pair of similar but oppositely disposed locking plates having locking shoulders on their radially outer axially upper ends disposed in said slot for non-pivotal radial reciprocation therein, a compression spring mounted between the locking plates for constantly urging them radially outwardly in said slot, a locking plate retracting and covering tube mounted within the outer casing for axial reciprocation with respect thereto, a core-holding tube pulling head fixedly connected to the upper end of the locking plate retracting tube, lost motion means connecting the lower part of the locking plate retracting tube to the lock support so that the locking plate retracting tube may be axially lifted to a limited degree relative to the lock support upon the initial lifting of the pulling head, the locking plate retracting tube having two diametrically disposed windows therein through which the outer ends of the locking plates can be pushed by the compression spring, a locking seat in the inner surface of the outer casing selectively lockingly receiving the shouldered outer ends of the locking plates, the lower outer surfaces of the locking plates axially below the shoulders thereon being inclined radially outwardly in an axially upward direction, and the lower edges of the windows in the locking plate retracting tube having formations which cooperate with the said inclined lower outer surfaces of the locking plates to thrust the locking plates radially inwardly against the action of the compression spring upon the axially upward displacement of the locking plate retracting tube relative to the locking support, whereby to disengage the locking plates from the locking seat in the outer casing. 